Portuguese Man-of-War Warnings Posted on South-Facing Beaches

Large numbers of Portuguese man-of-wars were found washed up on the south shore of the Vineyard this week, prompting The Trustees of Reservations to post notices at Norton Point beach in Edgartown.

“We are going to be putting up signage warning people they are back,” said Chris Kennedy, Vineyard superintendent for the Trustees, who manage and own a long stretch of south-facing shoreline from Norton Point to Wasque Reservation.

“We are finding them primarily on the south side, but it will not be unusual to find them at East Beach too,” Mr. Kennedy said.

He said it is early to find man-of-wars, which ordinarily wash up on beaches in the warmer months.

“They’re not uncommon, but we usually don’t see them until late summer,” Mr. Kennedy said. “I think there may be a warm core eddy that is pushing them in.”

Man-of-wars were seen on an ocean-facing beach at Squibnocket Wednesday morning.

The venomous Portuguese man-of-war is often called a jellyfish, but in fact it is a siphonophore, an animal made up of a colony of organisms working together. It derives its name from the gas-filled bladder that sits above the water and resembles an old warship under sail. The tentacles are covered with venom-filled nematocysts that the animal uses to paralyze and kill other fish and small sea creatures. It can deliver a painful sting to humans, either in the water or walking barefoot on the beach. The long, thin tentacles can be 30 feet in length.

Piping plover chick at Norton Point beach last summer. Plovers are nesting in large numbers this year.
— Lanny McDowell

A description on the National Geographic website says: “Man-of-wars are found, sometimes in groups of 1,000 or more, floating in warm waters throughout the world’s oceans. They have no independent means of propulsion and either drift on the currents or catch the wind with their pneumatophores. To avoid threats on the surface, they can deflate their air bags and briefly submerge."

“We have two families of chicks at the Gut, one plover nest at the elbow, two nests north of the Dike Bridge, one family of chicks running up and down East Beach, two nests on Leland Beach, one nest at Norton Point and two families at Norton Point,” Mr. Kennedy said. “They’re everywhere.”

Piping plovers are a state and federally protected species.

In a statement released late last week, the Trustees announced that while much of Cape Pogue and Norton Point has been closed to oversand vehicles to protect plover nests and chicks, after a detailed habitat study, the state Division of Fish and Wildlife and U.S. Fish and Wildlife will allow limited areas to remain open to vehicles.

About 5,000 feet of the Leland Beach bayside trail and about half the bayside trail north of the Dike Bridge are considered unsuitable foraging habitat for adults and chicks “due to the presence of large amounts of salt marsh or other impassable terrain. Thus, in these areas we may detour OSV traffic along the bayside trails when the bayside habitat is unsuitable for foraging by rare shorebirds or if a physical barrier exists (i.e. heavy tree/shrub vegetation) that precludes their ability to cross the barrier beach,” the statement said.

As an added protection measure, dogs are seasonally prohibited on some Trustees beaches, including at the Gut, portions of Norton Point Beach and all of Leland Beach. Dogs are not allowed on leashes or in vehicles in these areas from May 1 until mid-August.